Hard disk drives are widely used in computer and other systems to store information. These disk drives have a rigid disk of magnetic material on which binary data is written and stored for later retrieval. Data is written on the disk by moving a magnetic recording head to a position over the disk where the data is to be stored. The magnetic recording head then generates a magnetic field, which encodes the data into the magnetic material of the disk. Data is read from the disk by similarly positioning the magnetic recording head and then sensing the magnetic field of the disk's magnetic material. The positioning of the magnetic recording head is accomplished by continually spinning the disk while positioning a moveable arm over the surface of the disk. The moveable arm carries the magnetic recording head in a sweeping motion, generally across the radius of the disk. Read and write operations are synchronized with the rotation of the disk to insure that the data is read from and written to the desired location on the disk.
The magnetic recording head is generally encapsulated in a disk slider, which provides physical support for both the magnetic recording head and the electrical connections between the magnetic recording head and the remainder of the disk drive system. The disk slider also provides an air-bearing surface which permits the magnetic recording head to "fly" in close proximity to the surface of the spinning disk. Two parameters which are controlled by the design of the disk slider affect the amount of information which may be stored on the disk. One is the distance between the magnetic recording head imbedded in the disk slider and the surface of the disk. As this distance is reduced, the spacial density of binary information encoded on the disk may be increased. Another important slider characteristic is the precise positioning of the magnetic recording head within the body of the disk slider.
Disk sliders, typically formed from a ceramic wafer, generally have one or more parallel rails whose bottom surfaces form air-bearing surfaces capable of flying over the spinning disk. The magnetic recording head is mounted within the disk slider, and extends down through a rail, terminating at the air-bearing surface of the rail. Lapping processes attempt to create a smooth air-bearing surface by removing material from the magnetic recording head and rail surfaces. To form sliders with air-bearing surfaces that are precisely positioned relative to the structure of the magnetic recording head, the lapping process must be tightly controlled.
A technique for controlling the lapping process, described in U.S. Pat. No. 5,023,991, issued on Jun. 18, 1991, involves the use of an electrical lapping guide structure on the disk slider. Such techniques require that electrical contact be made to the electrical lapping guides during the lapping process. Relatively large contact pads are generally provided on the slider to allow this electrical contact to be made. However, as sliders become smaller to accommodate smaller disk drives, the electrical lapping guide contact pads can become a limiting factor because of the space on the slider that they occupy.
Making the electrical connections to the electrical lapping guide structure can also be difficult. This can be a particular problem when the sliders are lapped while still attached to the wafer from which they are formed, as described in U.S. Pat. No. 5,095,613 issued to Hussinger et al. on Mar. 17, 1992. Such a fabrication process may require relatively long connections to be made to the electrical lapping guides, extending across the face of the wafer. In addition to problems caused by the length of the bonds, the bonds must also be removed after the lapping process is completed and the slider is to be removed from the wafer. Removal of the wire bond generally leaves a scar and possibly some residue on the slider at the point of contact, presenting the risk of particulate breaking away from the bonding area at a later time.
The electrical lapping guide structures, beyond requiring contact pads and electrical connections, also occupy space on the disk slider. Thus, the use of existing electrical lapping guides limits the achievable reduction in the size of disk sliders which using these electrical lapping guides.
In light of the foregoing, it is desirable to have an apparatus for controlling the lapping of sliders which requires a minimum of space on the disk slider so as to allow the production of smaller disk sliders. It is desirable that both the electrical lapping guide structure and any associated contact area require a minimum of space on the disk slider. It is further desirable that the apparatus provide for a simple and reliable electrical contacting mechanism between the electrical lapping guide and the lapping device.